Ocular findings in four children with mucopolysaccharidosis I-Hurler (MPS I-H) treated early with haematopoietic stem cell transplantation

Purpose: To present visual functions and ocular findings in four children with mucopolysaccharidosis I-Hurler (MPS I- H) treated early with stem cell transplantation (SCT). Methods: Clinical ophthalmological evaluations including visual evoked potentials (VEPs) were carried out. Results: Stem cell transplantation was performed before 20 months of age. Ocular follow-up lasted 1.3-5.6 years (median 4.1 years). Reductions in corneal opacities were observed in all four children post-SCT, but a slight cloudiness persisted. Decreased visual acuity and high hyperopia (median + 6.25 dioptres, range + 4.0 D to + 7.5 D spherical equivalents) were noted in all children. Hyperopia was initially undetected due to dull retinal reflexes and photophobia. Two children developed esotropia, one with amblyopia. Keratometry, performed in two children, demonstrated subnormal values with a mean of 39.33 D (range 37.62-41.00 D). Visual evoked potentials and intraocular pressures were normal. Neither cataract nor dry eye were detected during follow-up. Conclusions: Early SCT appears to be beneficial in reducing, but not eliminating, corneal opacities in children with MPS I- H. Subjects are at risk of developing high hyperopia and esotropia. Hyperopia might be caused by the storage of glucosaminoglucans that increase corneal rigidity, thereby straightening the curvature of the cornea and reducing refractive power. As early diagnosis and treatment are very important, paediatric ophthalmologists should remember to rule out MPS I-H in children with corneal opacities.